1. Field of the Invention
The present disclosure is directed to low voltage surface preparation for atomic force probing and other measurement techniques. Advantages of low voltage collimated ion milling provides optimum surface finishing for scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM) applications, and for atomic force probing (AFP) and scanning electron microscope (SEM) nano-probing applications. More specifically, the present disclosure is directed to a unique SSRM holder or scanning probe microscopy (SPM) holder with a specially design polishing fixture with low voltage, collimated ion milling platen to accomplish low voltage inert collimated ion beam milling; secondary ion mass spectrometry (SIMS) endpoint detection associated with collimated ion milling, which employs rotating, angular focused low kV inert argon beam to the precise layer of interest. The SSRM/SCM holder fixes the surface scan area for iterative collimated ion milling removal and SSRM/SCM imaging of device fins without incident ion beam damage (which may shift the threshold voltage characteristics).
2. Description of Related Art
Surfaces suitable for atomic force probing (AFP), scanning electron microscope nano-probing, scanning probe microscopy (SPM) must be maintained in inert atmosphere but still permit iterative collimated ion milling/delayering with scanning ion mass spectroscopy (SIMS) endpoint detection.
Scanning capacitance metrology requires repeated polishing and reviewing of the sample in an SEM or SCM. Small angular misalignment between planes results in an unusable sample, which becomes more critical when there is only one sample available. Furthermore, tomography of device is needed for 3-D characterization of the samples. This is currently not possible in the prior art because of the angular variation between successive sample preparation steps.
No other means of surface preparation involving low voltage (50 eV to 300 eV) exists in the prior art that is capable of adequately addressing this matter. Furthermore, each sample is unique. Often there is a single failure site to be analyzed; and more often there is a need to repeat the preparation steps to expose the desired site. The prior art does not lend itself to adequate preparation of the sample to the correct location of the site; that is, there is at best an inconsistent approach to the region of interest. Additionally, the failure site may be lost through polishing the plane of interest.
It is further noted that the prior art is far removed from the methodology of the present disclosure insomuch as the prior art a) does not claim SPM/AFM/AFP methods of iterative inspection; b) does not teach an inert gas environment for protecting the surface of sample; c) does not specify a magnetized sample holder or the height of the magnetized sample holder for subsequent planar collimated ion milling, or chemical assisted ion beam etching (CAIBE), or SIMS endpoint detection, or for iterative delayering followed by SPM scanning; d) does not teach a flexible hose to prevent inversion of the container which contains samples during evacuation/purging with the inert gas; e) does not require the surface of the container to be corrosion resistant, flaking resistant, and free of debris/oxidization; and f) does not claim dual purpose containers for AFP/SEM nano-probing applications as well as SPM applications.